InterlockedCompareExchangeRelease function (Windows)

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InterlockedCompareExchangeRelease function

Applies to: desktop apps | Metro style apps

Performs an atomic compare-and-exchange operation on the specified values. The function compares two specified 32-bit values and exchanges with another 32-bit value based on the outcome of the comparison. The exchange is performed with release memory access semantics.

To operate on 64-bit values, use the InterlockedCompareExchangeRelease64 function.

Syntax

LONG __cdecl InterlockedCompareExchangeRelease(
  __inout  LONG volatile *Destination,
  __in     LONG Exchange,
  __in     LONG Comparand
);

Parameters

Destination [in, out]: A pointer to the destination value.
Exchange [in]: The exchange value.
Comparand [in]: The value to compare to Destination.

Return value

The function returns the initial value of the Destination parameter.

Remarks

This function compares the Destination value with the Comparand value. If the Destination value is equal to the Comparand value, the Exchange value is stored in the address specified by Destination. Otherwise, no operation is performed.

The variables for this function must be aligned on a 32-bit boundary; otherwise, this function will behave unpredictably on multiprocessor x86 systems and any non-x86 systems. See _aligned_malloc.

The interlocked functions provide a simple mechanism for synchronizing access to a variable that is shared by multiple threads. This function is atomic with respect to calls to other interlocked functions.

This function is implemented using a compiler intrinsic where possible. For more information, see the WinBase.h header file and _InterlockedCompareExchange_rel.

For processors that do not support release memory access semantics, this function is defined as a call to the InterlockedCompareExchange function. For more information, see WinBase.h.

Requirements

Minimum supported client	Windows Vista
Minimum supported server	Windows Server 2003
Header	WinBase.h (include Windows.h)